Abstract
Conventional single-voxel localization for MR spectroscopy (MRS) is restricted to selecting only rectangular-shaped regions of interest (ROIs). The complexity of tissue shapes of interest and the desire to maximize the signal-to-noise ratio (SNR) while minimizing partial-volume effects require more sophisticated localization techniques. A group of spatially selective RF pulses are proposed in this work for the measurement of spectra from regions of arbitrary shape based on using a radial trajectory in k-space. Utilizing a single k-line per excitation results in a broad spectroscopic bandwidth. However, spatial localization accuracy is compromised for nutation angles > 10° because of the small-tip-angle approximation of the Bloch equations. By interleaving multiple radial k-lines per excitation with nonselective refocusing pulses, one can achieve accurate localization for nutation angles up to 90° while simultaneously maintaining the spectral bandwidth. The technique is described and compared with existing localization methods, and in vivo results are demonstrated.
Original language | English (US) |
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Pages (from-to) | 19-26 |
Number of pages | 8 |
Journal | Magnetic resonance in medicine |
Volume | 58 |
Issue number | 1 |
DOIs | |
State | Published - Jul 2007 |
Externally published | Yes |
Keywords
- Arbitrary shape localization
- Bandwidth broadening
- Concatenation
- In vivo MRS
- Radial trajectory in k-space
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging